In a large bowl whisk together orange juice, orange zest. water, corn syrup, bitters, bourbon and vermouth until very well combined. Transfer to freezer and chill until very cold, at least 1½ hours.
Transfer chilled base into ice cream maker and churn until base looks like a soft sorbet with no visible excess liquid. It should look similar to a slushie you would get from a machine. Transfer churned base to an airtight container and chill in freezer until ready to serve.
When you're ready to serve, run the orange peel around the rim of your glass. Pour a spoonful of maraschino cherry juice in the bottom and our desired amount of slushie on top. Top with a spoonful of additional bourbon, if desired and a cherry on top. Drink immediately.
Note: *To, me the alcohol content of these is perfect. However, if you like more or less bourbon, feel free to adjust accordingly.